Where will you find gypsum rocks forged by fire and water millions of years ago?

If you answered Mars, you are correct. And if you answered Cuatro Ciénegas in Mexico, that is also true. Researchers have analyzed the bacterial communities that have survived in these inhospitable springs since the beginning of life on Earth and found that sulfur components from magma and minerals from the sea (carbonates and molecules with magnesium) helped form the gypsum. In the case of the Cuatro Ciénegas Basin, the magma under the seabed was very active - it allowed for the continent displacement during the Jurassic Period. The supercontinent Pangea opened up some 200 million years ago, pushing the hemisphere north from the equator where it is now.

Probing has detected gypsum in the Gale crater where Curiosity is currently located and it indicates that mineral-rich water was present and that sulfur was able to form. In the case of Mars, there is no confirmation of tectonic movement in its crust at any point, but a large meteorite likely crashed into its primitive sea.

"Cuatro Ciénegas is extraordinarily similar to Mars. As well as the Gale crater where Curiosity is currently located on its exploration of the red planet, this landscape is the home to gypsum formed by fire beneath the seabed," Valeria Souza, evolutionary ecologist at the National Autonomous University of Mexico (UNAM) told Servicio de Información y Noticias Científicas (SINC).Cuatro Ciénegas is one of few places on Earth 'similar' to that Martian environment. "This oasis in the middle of the Chihuahua desert is a time machine for organisms that, together as a community, have transformed our blue planet yet have survived all extinctions. How they have managed to do this can be revealed by their genes," says Souza.

The team have analyzed the metagenomes, the genome of the different bacterial communities that proliferate in these marshes by adapting parallel strategies to overcome survival challenges in a place with so little nutrients.

They found two communities in different pits, for example. One is 'green' and is formed by cyanobacteria and proteobacteria that have adapted to the lack of nitrogen. Another is 'red' and is made of Pseudomonas and other micro-organisms that live without hardly any phosphorous. There are also blue springs which are generally deeper and lacking in nutrients.

"Understanding the usage and exploitation strategies of phosphorous is necessary in understanding what could happen in extreme scenarios like on other planets where there is a possibly serious limitation to this and other nutrients," explains Luis David Alcaraz, Mexican researcher participating in the study from the Higher Public Health Research centre of Valencia, Spain.

The Cuatrociénegas Flora and Fauna Protection Area is a protected area but scientists and conservation groups still worry that its water is being depleted. "The bacterial communities have survived all types of cataclysms here such as the extinction of the dinosaurs or the majority of marine creatures. But, the only thing they are not adapted for is the lack of water," warns Souza.